1. Field of the Invention
The invention relates to a flushing device for a lavatory, having a flushing cistern in which is arranged a pressure vessel, which has a feed line for water and a discharge valve and in which at least some of the flushing water can be subjected to pressure and can be discharged through the discharge valve for flushing purposes.
2. Description of the Related Art
Conventional flushing cisterns have, as discharge valve, a float valve which is opened, for the purpose of triggering a flushing operation, for example by the actuation of a button. The flushing cistern is arranged above the toilet bowl which is to be flushed and, when the float valve is opened, the flushing water flows, as a result of the gravitational force, through a flushing pipe into the toilet bowl. However, flushing devices in the case of which the flushing water is subjected to pressure in the flushing cistern are also known. During flushing, the flushing water, as a result of the increased pressured, leaves the flushing cistern with an increased amount of energy and, correspondingly, the flushing action is greater.
For example, WO 98/39522 discloses a flushing cistern with a pressure vessel which has a base with a flushing valve. To prepare for a flushing operation, water from a supply line is introduced into the spherical pressure vessel. In addition, air is fed to the pressure vessel. This air is compressed when the water is introduced and builds up a pressure in the vessel. If the flushing valve is opened, then the water flows out of the pressure vessel as a result of the expanding air and, on account of the gravitational force, flows through the open flushing valve into the toilet bowl. As a result of the enhanced flushing action, less water can be used for flushing. The disadvantage with this flushing device is that it has to be designed for a comparatively high pressure, and that it is difficult to set the appropriate pressure in the vessel.
The applicant's WO 95/04196 discloses a flushing device which has a flushing cistern with two water outlets. Through one outlet, of the flushing processes, water is introduced as usual into the toilets bowl. The other outlet is connected to a nozzle which is arranged in a siphon of the toilet bowl and is intended to accelerate the water of the siphon during flushing. The flushing water is not subjected to pressure in the case of this flushing device. A flushing device with two outlets and a nozzle in the siphon involves comparatively high outlay and is not suitable in all cases.